One of the major objectives of the nanoscience and nanotechnology initiative is to develop general methodologies that can "effectively detect and analyze nanoscale entities of relevance to biomedicine". At present, supra-molecular complexes, structures with intrinsic flexibilities and/or heterogeneities and integral membrane proteins in the biological membrane remain a significant technological challenge. As such, the task of extracting "quantitative information (e.g., structural details) from biological nanoscale materials and machines" requires the development of more appropriate methods than those that must rely on ensemble averaging to achieve a high enough resolution. Here, we propose to develop an atomic force microscope (AFM) at cryogenic .temperatures to achieve a spatial resolution of 1 nm or better on individual complexes and nanoscale biological machines. The essential idea is to combine the high sensitivity of non-contact imaging and cryo-preservation of the native structure. Only with such an approach can the sharpness of an AFM tip be protected from degradation during imaging, a factor most critical for ultra-high resolution imaging. The immediate goal of this R21 application is to experimentally determine the feasibility of this approach and measure the fundamental parameters necessary for the design of robust instrumentation. If we succeed in developing this concept into a practical apparatus, such instrumentation will be a powerful method capable of resolving minute surface structural details (e.g., secondary structures) of individual complexes that cannot be surpassed by any other currently available approach. [unreadable] [unreadable]